如何将文本写入文件。 有什么办法可以打开文件写入文件？

Question

I have a foreach statement which executes 20,000 times, in each iteration I have to write a line to a file. The question is, Is there any way to open a file while writing to a file. Until and unless I close the stream I can't see the text in textfile. But I want to see the text without closing stream. Please anybody can help me.....

thanq in advance

var fileName = Path.GetTempPath();
streamWriter sw=new streamWriter(fileName + "\\sampleFile.txt",true);
for (int i = 0; i <= 20000; i++)
{                    
   sw.WriteLine("vinod" + i);                   
}

Answer 1

After each write to the file, call .Flush() on the stream. This will push the text to the file so you can see it during program execution. Should be noted that this is probably quite a performance hog, so don't do it unless you have to for some reason.

Answer 2

If you can compute the contents of the file at once and don't have to continuously log information to it, write the text to the file when the content is ready.

For example:

var fileName = Path.GetTempPath();
List<string> lines = new List<string>();
for (int i = 0; i <= 20000; i++)
{                    
   lines.Add("vinod" + i);                   
}

File.WriteAllLines(fileName, lines);

Otherwise go with flush for your stream or use File.AppendAllText (see MSDN ).

Answer 3

I wouldn't use file as a source for the viewer. If you are trying to do logger and viewer , then think about changing design:

1. Make some sort of source (but different than file, it can be file, but based the given conditions it is not optimal, as you going to update way too often) and make it accessible for both: logger and viewer. To example, use a string , which both can access.

2. Make event and make viewer in a way, that it will form his own source to view.

If viewer is a ListBox (to example), then 20000 items is pretty ok with second scenario. Add a line to file and send an event to ListBox at the same time, to update its content. No need to Flush() or something.

Whenever it gets bigger or if you what to provide advanced features for the viewer: filtering, reloading and such - the first scenario is better (virtual mode will be perfect for ListBox ).